JP4914088B2 - Water-based ink for inkjet recording - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous dispersion and a water-based ink reducing a bronze phenomenon and to provide a method for producing the aqueous dispersion. <P>SOLUTION: The aqueous dispersion for ink-jet recording comprises water-insoluble polymer particles (&alpha;) containing silica particles and a pigment except the silica particles. The water-based ink comprises the aqueous dispersion. The method for producing the aqueous dispersion for ink-jet recording comprises a step 1 of carrying out a dispersion treatment of a mixture of the silica particles with a water-insoluble polymer (&alpha;'), an organic solvent and water, a step 2 of removing the organic solvent from the resultant dispersion and affording water-insoluble polymer particles (&alpha;) containing the silica particles and a step 3 of mixing the resultant water-insoluble polymer particles (&alpha;) with the pigment except the silica particles. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to an aqueous dispersion for ink jet recording, a water-based ink, and a method for producing the same, which reduce the bronzing phenomenon of printed matter.

The ink jet recording method is a recording method in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle onto a recording member and attaching them. This method is easy and inexpensive to make full color, can use plain paper as a recording member, and has many advantages such as non-contact with the printed material.
Among them, from the viewpoint of weather resistance and water resistance of printed materials, those using pigment-based inks as colorants have become mainstream, but when pigments are used as colorants, reflected light depends on the observation angle of printed materials. A bronzing phenomenon may occur in which a color different from the original color of the pigment is observed. For example, a phthalocyanine pigment contained in cyan ink may cause the reflected light to be colored red, which may significantly deteriorate the image quality. The bronze phenomenon is described in detail in “Color Science Handbook” (University of Tokyo Press), page 777.
In order to improve this bronze phenomenon, an ink composition containing a polyether-modified polysiloxane and a sulfone group-containing (co) polymer emulsion has been proposed (see Patent Document 1). In addition, an ink containing a polycyclic aromatic heteroconjugated compound is disclosed (see Patent Document 2).
However, in any of these methods, there are concerns about adverse effects on print image quality due to changes in additives and pigments.

JP 2003-306620 A JP 2004-67903 A

  An object of the present invention is to provide an aqueous dispersion for ink jet recording and an aqueous ink that can reduce the bronzing phenomenon, and a method for producing the aqueous dispersion.

The present inventors have noticed that the bronzing phenomenon can be effectively reduced by using silica particles, and have found that the above problems can be solved.
That is, the present invention
(1) an aqueous dispersion for inkjet recording, comprising water-insoluble polymer particles (a) containing silica particles and a pigment excluding silica particles;
(2) A method for producing an aqueous dispersion for ink jet recording, comprising the aqueous ink containing the aqueous dispersion of (1), and (3) the following steps 1 to 3.
Step 1: Step of dispersing silica particles, water-insoluble polymer (I ′), organic solvent and water mixture Step 2: Water containing silica particles by removing the organic solvent from the dispersion obtained in Step 1 Step of obtaining an aqueous dispersion of insoluble polymer particles (a) Step 3: Step of mixing the aqueous dispersion of water-insoluble polymer particles (a) containing silica particles obtained in step 2 and a pigment excluding silica particles About.

The aqueous dispersion for inkjet recording and the water-based ink of the present invention can effectively reduce the bronzing phenomenon of printed matter.
Moreover, according to the manufacturing method of the present invention, an aqueous dispersion for ink jet recording that reduces the bronzing phenomenon of printed matter can be efficiently manufactured.

Hereinafter, the present invention will be described in detail.
(Pigments excluding silica particles (hereinafter also simply referred to as pigment))
In the aqueous dispersion for inkjet recording of the present invention, a pigment excluding silica particles is used, and an organic pigment is preferably used from the viewpoint of reducing the bronzing phenomenon.
Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthoraquinone pigments, and quinophthalone pigments.
Specific examples of preferred organic pigments include C.I. I. Pigment yellow, C.I. I. Pigment Red, C.I. I. Pigment violet, C.I. I. Pigment blue, and C.I. I. One or more types of products selected from the group consisting of pigment green are listed.

  Among organic pigments, a cyan pigment is preferably used and a phthalocyanine pigment is more preferable from the viewpoint of a large effect of reducing the bronze phenomenon. Examples of phthalocyanine pigments include metal-free phthalocyanine pigments; metal phthalocyanine pigments such as copper, aluminum, nickel, cobalt, iron, titanium, and tin, and unsubstituted or halogen-substituted phthalocyanine pigments such as chlorine and bromine. . More specifically, a copper phthalocyanine pigment is preferable, and C.I. I. One or more selected from the group consisting of CI Pigment Blue 15, 15: 1, 15: 2, 15: 3, 15: 4, 16 and 60 are preferred. Among these, from the viewpoint of durability against light, heat and solvent, C.I. I. Pigment Blue 15: 3 and 15: 4 are particularly preferable.

  In the case of using a cyan pigment, the intensity ratio of the intensity of [630 nm / intensity of 550 nm] in the reflection spectrum of the printed material with respect to the halogen lamp C light (hereinafter sometimes simply referred to as “reflection spectrum intensity ratio”) By adjusting to 4 or less, the bronze phenomenon can be significantly improved. Such a phenomenon is due to human visual characteristics. That is, among the color matching functions indicating the spectral sensitivity of the human eye, the peak of the color matching function having a large sensitivity in the red wavelength region is around 600 to 650 nm, and the green color is around 550 nm. When the ratio of both increases, the human eye perceives red. From the viewpoint of reducing the bronze phenomenon, the reflection spectrum intensity ratio between the two is preferably adjusted to 4 or less, more preferably 1 to 4, more preferably 1 to 3.5, and most preferably 1 to 3. .

  The average primary particle size of the pigment is preferably 10 to 100 nm, more preferably 20 to 90 nm, and still more preferably 30 to 80 nm from the viewpoints of pigment dispersibility, printing density, and scratch resistance. The average primary particle diameter of the pigment can be measured by the method described later.

(Silica particles)
The aqueous dispersion for ink-jet recording of the present invention is obtained by dispersing silica particles and a pigment together with a water-insoluble polymer, and the silica particles are present in the vicinity of the pigment. It is thought that there is an effect of the film, and it is considered that the bronzing phenomenon can be reduced by reducing the specular reflection light on the pigment surface.

  Silica particles can be classified into precipitated silica and fumed silica depending on the production method, and any of these can be used. All of these have hydrophilic properties because silanol groups (Si—O—H) are usually present on the surface thereof. In the present invention, the silica particles may be used as they are, but from the viewpoint of the effect of reducing the bronze phenomenon due to the presence of the silica particles in the vicinity of the pigment and the affinity with the water-insoluble polymer, the surface of the silica particles It is preferable to use hydrophobic silica in which at least a part of the surface is hydrophobized. Whether or not the front surface of the silica particles is hydrophobized can be determined by visual observation whether 1 g of the silica particles can be stably dispersed (25 ° C., 1 week) in 10 g of methyl ethyl ketone.

As a method for hydrophobizing the surface of silica particles, 1. a method of modifying silanol groups on the surface of silica particles with a hydrophobic group such as an alkylsilyl group having preferably 1 to 12 carbon atoms (for example, methylsilyl group, hexylsilyl group, etc.); The method etc. which coat | cover the silica particle surface with hydrophobic resin are mentioned.
Examples of the hydrophobizing agent for hydrophobizing the silica particle surface include organochlorosilane, organoalkoxysilane, organodisilazane, cyclic organopolysilazane, and linear organopolysiloxane.
The method of modifying the silanol group on the surface of silica with a hydrophobic group such as an alkylsilyl group is, for example, a method of reacting a water-dispersed silica colloid with an alkylsilanol alkali metal salt (see Japanese Patent Publication No. 7-33250); A method in which an organic solvent, a cationic surfactant, and an alkyltrialkoxysilane are added to a silica colloid, followed by azeotropic dehydration, followed by heating to reflux (refer to JP-A-6-73389); Examples thereof include a method of reacting an alkoxysilane, an organic silicon halide compound or the like (see JP-A-6-206720, JP-A-7-187647, etc.).

  In the silica particle in which the silanol group on the surface of the silica particle is modified with a hydrophobic group, the silanol group on the surface of the silica particle is preferably 5 mol% or more, more preferably 10 mol% or more, further preferably 20 mol% or more. It is modified with a group. As the alkylsilyl group for modifying the silanol group, a linear or branched alkyl group having 1 to 12 carbon atoms is preferable, and specifically, a methylsilyl group, an ethylsilyl group, an n-propylsilyl group, an i-propylsilyl group. N-butylsilyl group, t-butylsilyl group, i-butylsilyl group, pentylsilyl group, hexylsilyl group, 2-ethylhexylsilyl group, octylsilyl group, dodecylsilyl group and the like are preferable.

Since the silanol groups on the silica surface can ionically adsorb amino groups and imino groups, the ratio of silanol groups modified by the hydrophobic group is the di- sity for each silica before and after the modification reaction. It can be known by measuring the amount of adsorption of -n-butylamine.
From the viewpoint of reducing the bronze phenomenon, the average particle diameter of the silica particles is preferably 3 nm or more, 100 nm or less, more preferably 50 nm or less, more preferably 30 nm or less, still more preferably 20 nm or less, From these viewpoints, 3 to 100 nm is preferable, 3 to 50 nm is more preferable, 3 to 30 nm is more preferable, and 3 to 20 nm is still more preferable. The average particle size can be measured by the method described later.

(Silica-containing polymer particles (I))
The water-insoluble polymer particles (a) constituting the water-insoluble polymer particles (a) containing silica particles (hereinafter sometimes referred to as “silica-containing polymer particles (a)”) include water-insoluble vinyl polymers and water-insoluble esters. And a water-insoluble urethane polymer. Among these, a water-insoluble vinyl polymer is preferable from the viewpoint of the stability of the aqueous dispersion. In the present invention, the water-insoluble polymer means that when it is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., the dissolved amount is 10 g or less, preferably 5 g or less, more preferably 1 g or less. A polymer. When the water-insoluble polymer has a salt-forming group, the above-mentioned dissolution amount refers to the dissolution amount when the salt-forming group of the water-insoluble polymer is neutralized 100% with acetic acid or sodium hydroxide, depending on the type.

The water-insoluble polymer (A ′) preferably contains a structural unit derived from the salt-forming group-containing monomer (a), a structural unit derived from the hydrophobic monomer (b) and / or a structural unit derived from the macromer (c).
Examples of such a water-insoluble polymer (A ′) include a salt-forming group-containing monomer (a) (hereinafter sometimes referred to as “(a) component”), a hydrophobic monomer (b) (hereinafter referred to as “(b) component”). Water-insoluble vinyl polymer obtained by copolymerizing a monomer mixture (hereinafter sometimes referred to as “monomer mixture”) containing macromer (c) (hereinafter sometimes referred to as “component (c)”) Is preferred.
In addition, the water-insoluble polymer (I ′) is preferably a water-insoluble graft polymer containing a structural unit derived from the macromer (c) from the viewpoint of stabilizing the dispersion of silica particles.

The component (a) is used from the viewpoint of enhancing the dispersion stability of the resulting dispersion, and examples thereof include a cationic monomer and an anionic monomer. Specifically, those described in JP-A-9-286939, page 5, column 7, line 24 to page 8, column 8 line 29 can be used. Examples of the salt-forming group include a carboxy group, a sulfonic acid group, a phosphoric acid group, an amino group, and an ammonium group.
Representative examples of the cationic monomer include unsaturated amine-containing monomers and unsaturated ammonium salt-containing monomers, among which N, N-dimethylaminoethyl (meth) acrylate, N- (N ′, N '-Dimethylaminopropyl) (meth) acrylamide is preferred.

Representative examples of anionic monomers include unsaturated carboxylic acid monomers, unsaturated sulfonic acid monomers, unsaturated phosphoric acid monomers, and the like.
Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, and 2-methacryloyloxymethyl succinic acid.
Examples of unsaturated sulfonic acid monomers include styrene sulfonic acid, 2-acrylamide-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconate, and the like.

Examples of unsaturated phosphoric acid monomers include vinylphosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2-acryloyloxy Examples thereof include ethyl phosphate.
Among the anionic monomers, unsaturated carboxylic acid monomers are preferable, and acrylic acid or methacrylic acid is more preferable from the viewpoints of dispersion stability, dischargeability, and the like.
The said (a) component can be used individually or in combination of 2 or more types, respectively.

The hydrophobic monomer (b) is used from the viewpoint of improving water resistance and scratch resistance, and examples thereof include alkyl (meth) acrylate, alkyl (meth) acrylamide, and aromatic ring-containing monomers.
Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tertiary) butyl (meth) acrylate, (iso) amyl (meth) acrylate, Cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, (iso) stearyl (meth) acrylate, etc. (Meth) acrylic acid ester having an alkyl group having 1 to 22 carbon atoms.
Alkyl (meth) acrylamides include carbon atoms such as dimethyl (meth) acrylamide, diethyl (meth) acrylamide, dibutyl (meth) acrylamide, t-butyl (meth) acrylamide, octyl (meth) acrylamide, and dodecyl (meth) acrylamide. Examples include (meth) acrylamide having 1 to 22 alkyl groups.

Examples of aromatic ring-containing monomers include styrene monomers such as styrene, 2-methylstyrene and vinyltoluene, aryl esters of (meth) acrylic acid such as benzyl (meth) acrylate and phenoxyethyl (meth) acrylate, ethyl vinylbenzene, 4 Preferred are vinyl monomers having an aromatic hydrocarbon group having 6 to 22 carbon atoms such as -vinylbiphenyl, 1,1-diphenylethylene, vinylnaphthalene, chlorostyrene and the like.
In the present specification, “(iso or tertiary)” and “(iso)” mean that both of these groups are present and not present, and these groups are present. If not, it indicates normal. In addition, “(meth) acrylate” indicates that both acrylate and methacrylate are included.

As the component (b), an aromatic ring-containing monomer is preferable from the viewpoint of water resistance and scratch resistance, and among them, a styrene monomer (b-1) component is preferable, and styrene and 2-methylstyrene are more preferable. The content of the component (b-1) in the component (b) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight, from the viewpoint of improving printing density and marker resistance.
In addition, as the component (b), an aromatic ring-containing monomer is preferable from the viewpoint of improving the glossiness, among which the (meth) acrylic acid aryl ester (b-2) component is preferable, and has 7 to 22 carbon atoms, preferably (Meth) acrylate having an arylalkyl group having 7 to 18 carbon atoms, more preferably 7 to 12 carbon atoms, or 6 to 22 carbon atoms, preferably 6 to 18 carbon atoms, more preferably 6 to 12 carbon atoms. A (meth) acrylate having an aryl group is preferred. Specific examples of such a monomer include benzyl (meth) acrylate and phenoxyethyl (meth) acrylate. The content of the component (b-2) in the component (b) is preferably 10 to 100% by weight, more preferably 20 to 80% by weight from the viewpoint of improving glossiness.
The component (b) can be used alone or in combination of two or more, and it is also preferable to use the component (b-1) and the component (b-2) in combination.

Component (c) is used from the viewpoint of stably dispersing silica particles in water-insoluble polymer particles, and has a number average molecular weight of 500 to 100,000, preferably 1,000 to 10,000, and is not present at one end. Examples include macromers that are monomers having a polymerizable functional group such as a saturated group.
The number average molecular weight of the component (c) can be measured by gel permeation chromatography using polystyrene as a standard substance and tetrahydrofuran containing 50 mmol / L acetic acid as a solvent.
Specifically, as the macromer of component (c), the following (c-1) styrenic macromer, (c-2) alkyl (meth) acrylate macromer, (c-3) aromatic ring-containing (meth) acrylate Macromers, (c-4) silicon-based macromers, and the like.

(C-1) Styrenic Macromer The styrenic macromer means a macromer having a styrene monomer (referred to as c-1 monomer) such as styrene, α-methylstyrene, vinyltoluene and the like. Of the styrenic monomers, styrene is preferred.
Examples of the styrenic macromer include a styrene homopolymer having a polymerizable functional group at one end, and a copolymer of styrene and another monomer having a polymerizable functional group at one end. The polymerizable functional group present at one end is preferably an acryloyloxy group or a methacryloyloxy group, and by copolymerizing these, a water-insoluble graft polymer having a structural unit derived from a styrenic macromer can be obtained.

Other monomers include, for example, (1) acrylonitrile, (2) (meth) acrylic acid esters (c-2 monomer) described later, and (3) aromatic ring-containing (meth) acrylate monomers other than styrene (c -3 monomer).
In the side chain or the styrenic macromer, the content of the structural unit derived from the styrenic monomer is preferably 60% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight from the viewpoint of scratch resistance. That's it.
Examples of commercially available styrenic macromers include Toa Gosei Co., Ltd. trade names, AS-6 (S), AN-6 (S), HS-6 (S), and the like.

(C-2) Alkyl (meth) acrylate-based macromer An alkyl (meth) acrylate-based macromer has an alkyl group which may have a hydroxy group, preferably 1 to 22 carbon atoms, preferably 1 to 18 carbon atoms. , A macromer having a (meth) acrylic acid ester (c-2 monomer).
Specific examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (iso or tertiary). Examples include butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, and (iso) stearyl (meth) acrylate.
The side chain containing the structural unit derived from the c-2 monomer is obtained by copolymerizing an alkyl (meth) acrylate macromer having a polymerizable functional group at one end, such as a methyl methacrylate macromer or a butyl acrylate macromer. , Isobutyl methacrylate-based macromer, lauryl methacrylate-based macromer, and the like.

Alkyl (meth) acrylate-based macromers include alkyl (meth) acrylate homopolymers having a polymerizable functional group at one end, and alkyl (meth) acrylates and other monomers having a polymerizable functional group at one end. The acryloyloxy group or the methacryloyloxy group is preferable as the polymerizable functional group. Examples of the other monomer include (1) styrene monomer (c-1 monomer) described above and (3) aromatic ring-containing (meth) acrylate monomer (c-3 monomer) other than styrene described later.
In the side chain or in the alkyl (meth) acrylate macromer, the content of the structural unit derived from the (meth) acrylic ester is the largest, and from the viewpoint of scratch resistance, it is preferably 60% by weight or more, more preferably 70%. % By weight or more, particularly preferably 90% by weight or more.

(C-3) Aromatic ring-containing (meth) acrylate-based macromer The aromatic ring-containing (meth) acrylate-based macromer means a macromer having an aromatic ring-containing (meth) acrylate (c-3 monomer). As an aromatic ring containing (meth) acrylate, the monomer represented by following formula (1) is preferable.
CH ₂ = CR ¹ COOR ² (1)
(In the formula, R ¹ represents a hydrogen atom or a methyl group, and R ² represents an arylalkyl group having 7 to 22 carbon atoms or an aryl group having 6 to 22 carbon atoms, which may have a substituent. )
Specifically, benzyl (meth) acrylate, phenyl (meth) acrylate, 2-phenylethyl (meth) acrylate, phenoxyethyl (meth) acrylate, 1-naphthyl acrylate, 2-naphthyl (meth) acrylate, phthalimidomethyl (meta ) Acrylate, p-nitrophenyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-acryloyloxyethyl phthalate, and the like. Among these, benzyl (meth) acrylate is particularly preferable. These can be used alone or in combination of two or more.

A side chain containing a structural unit derived from an aromatic ring-containing (meth) acrylate can be obtained by copolymerizing an aromatic ring-containing (meth) acrylate-based macromer having a polymerizable functional group at one end.
An aromatic ring-containing (meth) acrylate-based macromer is a homopolymer of an aromatic ring-containing (meth) acrylate having a polymerizable functional group at one end, and an aromatic ring-containing (meth) acrylate having a polymerizable functional group at one end And other monomers, and the polymerizable functional group is preferably an acryloyloxy group or a methacryloyloxy group. Examples of the other monomer include (1) styrene monomer (c-1 monomer), (2) (meth) acrylic acid ester (c-2 monomer), and the like.
In the side chain or in the aromatic ring-containing (meth) acrylate macromer, the content of the structural unit derived from the aromatic ring-containing (meth) acrylate is the largest.

(C-4) Silicon-based macromer The water-insoluble polymer (I ') used in the present invention may have an organopolysiloxane chain as a side chain. This side chain can be obtained, for example, by copolymerizing a silicone macromer having a polymerizable functional group at one end, preferably represented by the following formula (2).
_{CH 2 = C (CH 3)} -COOC 3 H 6 - [Si (CH _{3) 2} -O] _{t -Si (CH 3) 3 (} 2)
(Wherein t represents a number of 8 to 40)
Among the macromers, a styrenic macromer having a polymerizable functional group at one end is preferable from the viewpoint of high affinity with the pigment and improving storage stability.
In the present invention, the above macromers may be used alone or in combination of two or more.
When the water-insoluble polymer (I ') used in the present invention is a water-insoluble graft polymer, the weight ratio of [main chain / side chain] is 1/1 from the viewpoint of improving scratch resistance and storage stability. It is preferably ˜20 / 1, more preferably 3/2 to 15/1, particularly preferably 2/1 to 10/1. It is calculated that the polymerizable functional group is contained in the side chain.

In the present invention, the monomer mixture containing the components (a), (b), and (c) further contains a hydroxyl group-containing monomer (d) (hereinafter sometimes referred to as “component (d)”). Is preferred.
The component (d) increases the dispersion stability of the aqueous dispersion. Examples of the component (d) include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and polyethylene glycol (n = 2 to 30, n represents the average number of moles added of the oxyalkylene group. The same)) (meth) acrylate, polypropylene glycol (n = 2-30) (meth) acrylate, poly (ethylene glycol (n = 1-15) / propylene glycol (n = 1-15)) (meth) acrylate, etc. Can be mentioned. Among these, 2-hydroxyethyl (meth) acrylate, polyethylene glycol monomethacrylate, and polypropylene glycol methacrylate are preferable.

The monomer mixture may further contain a monomer (e) represented by the following formula (3) (hereinafter sometimes referred to as “component (e)”).
^{_{CH 2 = C (R 3)}} COO (R 4 O) p R 5 (3)
(Wherein R ³ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R ⁴ represents a divalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, R ⁵ Represents a monovalent hydrocarbon group having 1 to 30 carbon atoms which may have a hetero atom, but p represents the average number of added moles, and is 1 to 60, preferably 1 to 30.)
The component (e) expresses the effect of improving the discharge stability of the water-based ink.
In formula (3), examples of the hetero atom that R ⁴ or R ⁵ may have include a nitrogen atom, an oxygen atom, a halogen atom, and a sulfur atom.
Typical examples of the group represented by R ⁴ or R ⁵ include an aromatic group having 6 to 30 carbon atoms, a heterocyclic group having 3 to 30 carbon atoms, an alkylene group having 1 to 30 carbon atoms, and the like. It may have a substituent. These groups may be a combination of two or more. Examples of the substituent include an aromatic group, a heterocyclic group, an alkyl group, a halogen atom, and an amino group.

R ⁴ is a phenylene group which may have a substituent having 1 to 24 carbon atoms, a C 1 to 30 carbon atom, preferably an aliphatic alkylene group having 1 to 20 carbon atoms, or a carbon number having an aromatic ring. A 7-30 alkylene group and a C4-C30 alkylene group which has a heterocyclic ring are mentioned preferably. Particularly preferred specific examples of the R ⁴ O group include an oxyethylene group, an oxy (iso) propylene group, an oxytetramethylene group, an oxyheptamethylene group, an oxyhexamethylene group, or a carbon number of two or more of these oxyalkylenes. ˜7 oxyalkylene groups and oxyphenylene groups.
R ⁵ includes a phenyl group, an aliphatic alkyl group having 1 to 30 carbon atoms, preferably a branched chain having 1 to 20 carbon atoms, an alkyl group having 7 to 30 carbon atoms having an aromatic ring, or A C4-C30 alkyl group which has a heterocyclic ring is mentioned preferably. More preferred examples of R ⁵ include alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, (iso) propyl group, (iso) butyl group, (iso) pentyl group and (iso) hexyl group, phenyl Groups and the like.

  Specific examples of the component (e) include methoxypolyethylene glycol (p is 1 to 30 in the above formula (3)) (meth) acrylate, methoxypolytetramethylene glycol (p = 1 to 30) (meth) acrylate, and ethoxypolyethylene. Glycol (p = 1-30) (meth) acrylate, (iso) propoxypolyethylene glycol (p = 1-30) (meth) acrylate, butoxypolyethylene glycol (p = 1-30) (meth) acrylate, octoxypolyethylene glycol (P = 1-30), methoxypolypropylene glycol (p = 1-30) (meth) acrylate, methoxy (ethylene glycol / propylene glycol copolymer) (p = 1-30, in which the ethylene glycol moiety is 1-29 ) (Meth) acrylate It is done. Among these, methoxypolyethylene glycol (p = 1-30) (meth) acrylate is preferable.

Specific examples of commercially available (d) and (e) components include: Shin-Nakamura Chemical Co., Ltd., polyfunctional acrylate monomer (NK ester) M-40G, 90G, 230G; Mer series, PE-90, 200, 350, PME-100, 200, 400, 1000, PP-1000, PP-500, PP-800, AP-150, AP-400, AP-550, AP-800, 50PEP -300,50POEP-800B etc. are mentioned.
The component (d) and the component (e) can be used alone or in combination of two or more.

The contents of the components (a) to (e) in the monomer mixture are preferably as follows.
The content of component (a) is preferably 3 to 30% by weight, more preferably 4 to 20% by weight, from the viewpoint of dispersion stability of the resulting dispersion.
The content of component (b) is preferably 10 to 70% by weight, more preferably 15 to 60% by weight, from the viewpoint of water resistance and scratch resistance.
The content of the component (c) is preferably 1 to 25% by weight, more preferably 5 to 20% by weight, from the viewpoint of stably dispersing the silica particles in the water-insoluble polymer fine particles.
The weight ratio ((a) / [(b) + (c)]) of the content of the component (a) and the total content of the components (b) and (c) is the long-term storage of the resulting water-based ink. From the viewpoints of stability, dischargeability and the like, it is preferably 0.01 to 1, more preferably 0.02 to 0.67, and still more preferably 0.03 to 0.50.

The content of the component (d) is preferably 5 to 40% by weight, more preferably 7 to 20% by weight from the viewpoints of dischargeability and print density.
The content of the component (e) is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, from the viewpoints of dischargeability and dispersion stability.
From the viewpoint of stability in water, the total content of the component (a) and the component (d) is preferably 6 to 60% by weight, more preferably 10 to 50% by weight.
The total content of the component (a) and the component (e) is preferably 6 to 75% by weight, more preferably 13 to 50% by weight from the viewpoints of dispersion stability in water, dischargeability, and the like.
The total content of the component (a), the component (d), and the component (e) is preferably 6 to 60% by weight, more preferably 7 to 7% from the viewpoints of dispersion stability in water, print density, and dischargeability. 50% by weight.
The content of the components derived from the components (a) to (e) in the water-insoluble polymer is the same as the content of the components.

The water-insoluble polymer (I ') is produced by copolymerizing the monomer mixture by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. Among the polymerization methods, effects such as high printing density and high bleed resistance can be suitably obtained in the case of the solution polymerization method.
As the solvent used in the solution polymerization method, a polar organic solvent having a high affinity for the water-insoluble polymer is preferable, and the solubility in water at 20 ° C. is preferably 50% by weight or less, and more preferably 5% by weight or more. Examples of the polar organic solvent include aliphatic alcohols such as butoxyethanol; aromatics such as toluene and xylene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate. Among these, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, butoxyethanol, or a mixed solvent of one or more of these with water is preferable.

In the polymerization, azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), tert-butyl peroxyoctoate, dibenzoyl oxide, etc. Known polymerization initiators such as organic peroxides can be used.
The amount of the polymerization initiator is preferably 0.001 to 5 mol, more preferably 0.01 to 2 mol, per mol of the monomer mixture.
In the polymerization, a known polymerization chain transfer agent such as mercaptans such as octyl mercaptan and 2-mercaptoethanol, and thiuram disulfide can be further added.
The polymerization conditions of the monomer mixture vary depending on the type of polymerization initiator, monomer, and solvent used, but the polymerization temperature is usually 30 to 100 ° C., preferably 50 to 80 ° C., and the polymerization time is 1 to 20 hours. is there. The polymerization atmosphere is preferably a nitrogen gas atmosphere or an inert gas atmosphere such as argon.
After completion of the polymerization reaction, the produced polymer can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation.

The weight-average molecular weight of the obtained water-insoluble polymer (I ′) is preferably from 5,000 to 500,000, more preferably from 10,000 to 400,000, from the viewpoints of pigment dispersion stability, water resistance, dischargeability, and the like. More preferred is 10,000 to 300,000.
The weight average molecular weight of the polymer was measured using polystyrene as a standard substance by a gel permeation chromatography method using dimethylformamide in which 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide were dissolved as a solvent. Is done.

  When the water-insoluble polymer (A ′) has a salt-forming group derived from the salt-forming group-containing monomer (a), it is neutralized with a neutralizing agent. As the neutralizing agent, an acid or a base can be used depending on the kind of the salt-forming group in the polymer. For example, hydrochloric acid, acetic acid, propionic acid, phosphoric acid, sulfuric acid, lactic acid, succinic acid, glycolic acid, Examples include acids such as gluconic acid and glyceric acid, bases such as lithium hydroxide, sodium hydroxide, potassium hydroxide ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, trimethylamine, triethanolamine, and tributylamine. .

The degree of neutralization of the salt-forming group is preferably 10 to 200%, more preferably 20 to 150%, and particularly preferably 50 to 150%. Here, the degree of neutralization can be determined by the following formula when the salt-forming group is an anionic group.
{[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [acid value of polymer (KOH mg / g) × polymer weight (g) / (56 × 1000)]} × 100
On the other hand, when the salt-forming group is a cationic group, it can be obtained by the following formula.
[[Weight of neutralizing agent (g) / equivalent of neutralizing agent] / [amine value of polymer (HCL mg / g) × weight of polymer (g) / (36.5 × 1000)]] × 100
The acid value and amine value can be calculated from the structural unit of the polymer, but can also be determined by a method of titrating by dissolving the polymer in an appropriate solvent (for example, methyl ethyl ketone).

(Method for producing silica-containing water-insoluble polymer particles (i))
As described above, when the silica particles are contained in the water-insoluble polymer particles (a), the bronzing phenomenon can be effectively reduced and excellent dispersion stability can be obtained.
The silica-containing polymer particles (A) are preferably produced by the following step 1 and step 2.
Step 1: A step of dispersing a mixture of silica particles, a water-insoluble polymer (I ′), an organic solvent and water Step 2: A step of removing the organic solvent from the dispersion obtained in Step 1 In Step 1 above First, silica particles, a water-insoluble polymer (I ') (hereinafter also simply referred to as a water-insoluble polymer), an organic solvent and water are mixed. Preferably, the water-insoluble polymer is dissolved in an organic solvent, and then Silica particles, water, and, if necessary, a neutralizing agent, a surfactant and the like are added to the organic solvent and mixed to obtain an oil-in-water dispersion.

In the above mixture, the content of silica particles is preferably 2 to 40% by weight, more preferably 2 to 20% by weight, and the content of the organic solvent is preferably 10 to 70% by weight, 50% is more preferable, the content of the water-insoluble polymer is preferably 2 to 40% by weight, more preferably 2 to 20% by weight, and the content of water is preferably 10 to 70% by weight, More preferred is ˜60% by weight.
When the water-insoluble polymer has a salt-forming group, it is preferable to use a neutralizing agent, but the water-insoluble polymer may be neutralized with a neutralizing agent in advance. The degree of neutralization is not particularly limited, but it is usually preferable to neutralize so that the liquid dispersion of the finally obtained water dispersion is neutral, for example, pH is 4.5 to 10. The pH can also be determined by the desired degree of neutralization of the water-insoluble polymer.

Preferred examples of the organic solvent include alcohol solvents, ketone solvents, and ether solvents, and those having a solubility in water at 20 ° C. of 50% by weight or less and 10% by weight or more are preferable.
Specifically, examples of the alcohol solvent include ethanol, isopropanol, n-butanol, tertiary butanol, isobutanol, diacetone alcohol and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of the ether solvent include dibutyl ether, tetrahydrofuran, dioxane and the like. Among these solvents, isopropanol, acetone and methyl ethyl ketone are preferable, and methyl ethyl ketone is particularly preferable. These solvents can be used alone or in admixture of two or more.

The method for dispersing the mixture in Step 1 is not particularly limited as long as it can be atomized so as to obtain water-insoluble polymer particles having a desired average particle diameter.
Examples of the disperser include a kneader such as a roll mill, a kneader, and an extruder, a disperser such as a sand mill and a bead mill, a high pressure homogenizer such as a chamber type, and the like. Among these, from the viewpoint of uniformly mixing the silica particles and the pigment, a method of wet pulverization with a disperser using a dispersion medium is preferable. Furthermore, it is also preferable to adopt a method of dispersing by a high-pressure homogenizer after wet pulverization if necessary.

The material of the dispersion medium is preferably ceramic beads such as titania (TiO ₂ ), zirconia (ZrO ₂ ), zircon (ZrSiO ₄ ) alumina (Al ₂ O ₃ ), particularly titania (TiO ₂ ), from the viewpoint of hardness and the like. Zirconia (ZrO ₂ ) is preferred. The particle size of the dispersion medium is usually 30 to 500 μm, preferably 30 to 400 μm.
In the wet pulverization dispersion, the weight ratio of the dispersion medium / dispersion liquid (including all dispersions such as silica particles, polymer, water, and organic solvent) is usually 10/1 to 4 / from the viewpoint of uniformly mixing the silica particles. 6, preferably 10/1 to 5/5.
The peripheral speed of the disperser using the dispersion medium is the speed of the outer periphery of the stirring blade when it has a stirring blade. In the present invention, it is preferably 3 to 30 m / sec, more preferably 5 to 25 m / sec. It is. When there is no stirring blade, it is the rotational speed of the container, and in the present invention, it is preferably a speed of 0.1 to 1 m / sec.
The dispersion time is preferably 1 to 15 hours, and more preferably 2 to 10 hours, from the viewpoint of uniformly mixing the silica particles. From the same point, the temperature during dispersion is preferably 0 to 60 ° C, more preferably 5 to 30 ° C.

In the step 2, the organic solvent is distilled off from the dispersion obtained in the step 1 to form an aqueous system, thereby obtaining an aqueous dispersion of water-insoluble polymer particles (i) having a desired average particle size. The organic solvent contained in the aqueous dispersion can be removed by a general method such as distillation under reduced pressure. The organic solvent in the obtained aqueous dispersion is substantially removed, and the residual amount of the organic solvent is preferably 0.1% by weight or less, more preferably 0.01% by weight or less.
Moreover, it is preferable to remove coarse particles by filtering the obtained aqueous dispersion.

The obtained aqueous dispersion is an aqueous dispersion of silica-containing water-insoluble polymer particles (A). That is, the silica-containing water-insoluble polymer particles (A) are dispersed in water as a main solvent. Here, the form of the silica-containing water-insoluble polymer particles (A) is not particularly limited, and any form may be used as long as the particles are formed by at least silica particles and the water-insoluble polymer (A ′). Particle form in which silica particles are encapsulated in '), particle form in which silica particles are uniformly dispersed in water-insoluble polymer (b), particle form in which silica particles are exposed on the surface of water-insoluble polymer particle (b), etc. Are included.
The average particle diameter of the obtained silica-containing water-insoluble polymer particles (A) is preferably 10 to 200 nm, more preferably 30 to 130 nm, and still more preferably 50 to 120 nm, from the viewpoint of preventing clogging of printer nozzles. is there. The average particle diameter can be determined by a measurement method described later.

(Aqueous dispersion for water-jet recording / aqueous ink containing silica-containing water-insoluble polymer particles (i) and pigment)
The aqueous dispersion for ink-jet recording of the present invention preferably comprises steps 1 and 2 for obtaining silica-containing water-insoluble polymer particles (a), and step 3 for mixing the obtained water-insoluble polymer particles (a) and a pigment. Specifically, it can be obtained by a production method having the following steps 1 to 3.
Step 1: Dispersing a mixture of silica particles, water-insoluble polymer (I '), organic solvent and water Step 2: Removing the organic solvent from the dispersion obtained in Step 1 to obtain silica particles Step 3 of obtaining an aqueous dispersion of water-insoluble polymer particles (a) containing: Step 3: Step of mixing the aqueous dispersion of water-insoluble polymer particles (a) containing silica particles obtained in step 2 and a pigment.

Steps 1 and 2 are as described above. Step 3 is a step of mixing the silica-containing water-insoluble polymer particles (A) and the pigment. In particular, it is preferable to mix with silica-containing water-insoluble polymer particles (A) and at least one pigment selected from the group consisting of the following (1) to (3) or a dispersion thereof.
(1) A pigment dispersed in water with a surfactant, a pigment derivative or a water-soluble polymer (2) A self-dispersing pigment in which a hydrophilic group is bonded to the pigment directly or through another atomic group (3 ) Water dispersion of pigment-containing water-insoluble polymer particles (b) (hereinafter sometimes referred to as “pigment-containing water-insoluble polymer particles (b)”)

Examples of the surfactant used in the pigment dispersion (1) include anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants, and pigment derivatives include An azo derivative, a diazo derivative, a phthalocyanine derivative, a quinacridone derivative, an isoindolinone derivative, a dioxazine derivative, a perylene derivative, a perinone derivative, a thioindigo derivative, an anthraquinone derivative, a quinophthalone derivative having an ionic functional group or a salt of an ionic functional group Can be mentioned.
The water-soluble polymer is a polymer whose dissolved amount exceeds 10 g, preferably 20 g or more, more preferably 30 g or more when dissolved in 100 g of water at 25 ° C. When the water-soluble polymer has a salt-forming group such as a carboxy group or an ammonium group, the above-mentioned dissolution amount is 100% neutralized with acetic acid or sodium hydroxide according to the type of the water-soluble polymer. The amount of dissolution.

Examples of the water-soluble polymer include (i) a water-soluble polymer obtained by subjecting a sulfonated product obtained by sulfonating a polynuclear aromatic compound or a mononuclear aromatic compound to formalin condensation, and then preferably neutralizing; (ii) carboxy A water-soluble polymer having a group is preferred. Specific examples of the polymer (i) include polynaphthalene sulfonic acid (salt) typified by sodium salt of β-naphthalenesulfonic acid formalin condensate, and include Demol NL and Demol made by Kao Corporation. Commercial products such as N and demall MS (trade name) can be used. The polymer of (ii) includes (meth) acrylic acid (salt) polymer represented by polyacrylic acid and its copolymer, sodium salt of styrene and maleic acid copolymer, diisobutylene and maleic acid copolymer. A maleic acid (salt) polymer represented by a combined sodium salt and a copolymer thereof may be mentioned, and specifically, Pois 520, Pois 521, Pois 530 and the like manufactured by Kao Corporation are preferable.
The water-soluble polymer preferably has a weight average molecular weight of 2,000 to 50,000 from the viewpoint of dispersibility. The weight average molecular weight of the water-soluble polymer was measured using polystyrene as a standard substance by a gel chromatography method using dimethylformamide in which 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide were dissolved as a solvent. can do.

In the water dispersion (3), examples of the water-insoluble polymer (b ') constituting the pigment-containing water-insoluble polymer particles (b) include water-insoluble vinyl polymers, water-insoluble ester polymers, water-insoluble urethane polymers, and the like. Can be mentioned. Among these, a water-insoluble vinyl polymer is preferable from the viewpoint of the stability of the aqueous dispersion.
The water-insoluble polymer (ro ′) preferably contains a structural unit derived from the salt-forming group-containing monomer (a), a structural unit derived from the hydrophobic monomer (b) and / or a structural unit derived from the macromer (c), As the preferred range, monomer compound and the like, the same water-insoluble polymer (A ′) constituting the above-mentioned water-insoluble polymer particles (A) can be used. However, the water-insoluble polymer (B ′) and the water-insoluble polymer (A ′) may be the same or different.

The water-insoluble polymer particles (b) containing the pigment can be preferably produced by the following steps I and II.
Step I: Dispersing a mixture of a pigment, a water-insoluble polymer (b '), an organic solvent and water Step II: A step of removing the organic solvent from the dispersion obtained in Step I In Steps I and II The preferred quantitative ratios, production conditions, and the like of each component are the same as in the case where the silica particles are replaced with pigments in the above-described Steps 1 and 2.
The aqueous dispersion obtained in Step II is an aqueous dispersion of pigment-containing water-insoluble polymer particles (b). That is, the water-insoluble polymer particles (B) containing the pigment are dispersed in water as the main solvent. Here, the form of the water-insoluble polymer particles (B) containing the pigment is not particularly limited, as long as the particles are formed by at least the pigment and the water-insoluble polymer (B '). For example, the water-insoluble polymer (B') The particle form in which the pigment is encapsulated, the particle form in which the pigment is uniformly dispersed in the water-insoluble polymer (b), the particle form in which the pigment is exposed on the surface of the water-insoluble polymer particle (b), and the like are included.

The average particle diameter of the pigment-containing water-insoluble polymer particles (b) is preferably 30 to 200 nm, more preferably 50 to 130 nm, and still more preferably 60 to 120 nm, from the viewpoint of preventing clogging of the printer nozzle and the printing density. . The particle size can be determined by a measurement method described later.
In the present invention, among the pigments (1) to (3) or dispersions thereof, it is preferable to use the aqueous dispersion of the pigment-containing water-insoluble polymer particles (b) of (3). It is preferable from the viewpoint of dispersion stability.

The content of each component in the aqueous dispersion for inkjet recording of the present invention or in the water-based ink is as follows.
The content of silica particles is preferably 0.1 to 10% by weight, more preferably 0.5 to 8% by weight, and still more preferably 1 to 5% by weight, from the viewpoint of reducing the bronze phenomenon.
The content of the pigment is preferably 1 to 10% by weight, more preferably 2 to 10% by weight, still more preferably 3 to 10% by weight, and further preferably 3 to 8% by weight from the viewpoint of increasing the printing density.

The content ratio of silica particles to pigment (silica particles / pigment) is preferably 1/100 to 5/1, more preferably 1/10 to 3/1, and still more preferably from the viewpoint of reducing the bronze phenomenon. 1/4 to 2/1.
When the pigment is contained in the water-insoluble polymer particles (b), the content ratio of the pigment to the water-insoluble polymer (b ') (water-insoluble polymer (b') / pigment) is the print density, scratch resistance and dispersion. From the viewpoint of enhancing the stability, the weight ratio is preferably 5/95 to 90/10, more preferably 10/90 to 75/25, and still more preferably 20/80 to 50/50.
The content ratio of the silica particles to the water-insoluble polymer (I ′) (water-insoluble polymer (I ′) / silica particles) is 5/95 to 90/10 in terms of weight ratio from the viewpoint of improving scratch resistance and dispersion stability. It is preferably 10/90 to 75/25, more preferably 20/80 to 50/50.
The total content of the water-insoluble polymer particles (A) and (B) is preferably 0.5 to 15% by weight, more preferably 1 to 12% by weight, from the viewpoint of dischargeability and dispersion stability of silica particles and pigments. More preferably, it is 1 to 10% by weight.

The water dispersion of the present invention may be used as a water-based ink containing water as a main solvent as it is, but a wetting agent, a penetrating agent, a dispersant, a viscosity modifier, an antifoaming agent, which are usually used in water-based inks for inkjet recording, An antifungal agent, an antirust agent, etc. can be added and used as water-based ink.
The water content in the aqueous dispersion of the present invention is preferably 30 to 90% by weight, more preferably 40 to 85% by weight.
The water content in the water-based ink of the present invention is preferably 30 to 95% by weight, more preferably 40 to 90% by weight.

The surface tension (20 ° C.) of the aqueous dispersion and aqueous ink of the present invention is preferably 30 to 65 mN / m, more preferably 35 to 60 mN / m as the aqueous dispersion, and preferably as the aqueous ink. It is 23-50 mN / m, More preferably, it is 23-45 mN / m, More preferably, it is 23-40 mN / m, More preferably, it is 23-30 mN / m.
The viscosity (20 ° C.) of 20% by weight (solid content) of the aqueous dispersion of the present invention is preferably 1 to 12 mPa · s, more preferably 1 to 9 mPa · s, in order to obtain a preferable viscosity when used as an aqueous ink. Preferably, 2 to 6 mPa · s is more preferable, and 2 to 5 mPa · s is still more preferable.
The viscosity (20 ° C.) of the water-based ink of the present invention is preferably 2 to 12 mPa · s, more preferably 2.5 to 10 mPa · s, and preferably 2.5 to 6 mPa · s in order to maintain good ejection properties. Further preferred.

In the following production examples, examples and comparative examples, “parts” and “%” represent “parts by weight” and “% by weight”, respectively, unless otherwise specified.
Production Example 1 Production of water-insoluble polymer 46 parts of benzyl methacrylate (manufactured by Wako Pure Chemical Industries, Ltd., reagent), 14 parts of methacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd., reagent), styrene macromer (manufactured by Toagosei Co., Ltd., product) Name: AS-6S, number average molecular weight: 6000, 50% by weight (solid content), 40 parts of polymerizable functional group: methacryloyloxy group, and polypropylene glycol monomethacrylate (addition moles of propylene oxide = average 9 moles, terminal) 100 parts of a monomer comprising 20 parts of a hydroxyl group, 20 parts of an organic solvent (methyl ethyl ketone), 1 part of a polymerization chain transfer agent (2-mercaptoethanol, manufactured by Wako Pure Chemical Industries, Ltd., reagent), a polymerization initiator (2, 2 ′ -10% of the total amount of azobis (2,4-dimethylvaleronitrile), 1 part by Wako Pure Chemical Industries, Ltd., V-65) Were mixed and nitrogen gas substitution was sufficiently performed to obtain a mixed solution.
On the other hand, the remaining 90% was used in the dropping funnel, and polymerization was carried out while dropping at 75 ° C. with stirring. After about 2 hours at 75 ° C. from the end of dropping, the mixture was aged at 80 ° C. for 1 hour to obtain a water-insoluble polymer (weight average molecular weight 18,000).

Example 1
50 parts of the polymer obtained by drying the polymer solution obtained in Production Example 1 under reduced pressure was dissolved in 70 parts of methyl ethyl ketone, and then 30% silica sol (hydrophobized silica (hydrophobized by Nissan Chemical Industries, Ltd .; product) Name MEK-ST) 167 parts, neutralized with a neutralizing agent (5N aqueous sodium hydroxide solution) 8.2 parts (neutralization degree 75%) and 230 parts ion-exchanged water to neutralize the salt-forming groups. The resulting mixture was dispersed for 2 hours at a peripheral speed of 15 m / s using Picomill, Asada Iron Works Co., Ltd. The resulting mixture was dispersed for 10 passes at a pressure of 200 MPa with a microfluidizer (trade name, manufactured by Microfluidics). .
After adding 250 parts of ion-exchanged water to the obtained dispersion and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, a part of water was further removed, and a 5 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) and filtered with a 25 mL needleless syringe (Terumo Co., Ltd.), and by removing coarse particles, silica-containing polymer particles having a solid content concentration of 20% An aqueous dispersion was obtained. The average particle diameter of the silica-containing polymer particles was 75 nm.

Next, 25 parts of the polymer obtained by drying the polymer solution obtained in Production Example 1 under reduced pressure is dissolved in 70 parts of methyl ethyl ketone, and 4.1 parts of neutralizing agent (5N aqueous sodium hydroxide solution) is contained therein. 75%) and 230 parts of ion-exchanged water were added to neutralize the salt-forming groups, and further 75 parts of a copper phthalocyanine pigment (Pigment Blue 15: 3, average primary particle size 70 nm) was added and predispersed with a disper. Then, asada ironworks Co., Ltd. Picomill (zirconia beads (particle size: 50 μm) filling rate 80%, temperature 10 ° C.) was subjected to dispersion treatment at a peripheral speed of 15 m / s at the tip of the stirring blade for 2 hours. The obtained mixture was subjected to 10-pass dispersion treatment at a pressure of 200 MPa with a microfluidizer (trade name, manufactured by Microfluidics).
After adding 250 parts of ion-exchanged water to the obtained pigment dispersion and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, and a part of the water was removed, and a 5 μm filter (acetylcellulose membrane, outer diameter). : Pigment-containing polymer particles having a solid content concentration of 20% by filtering with a 25 mL needleless syringe (made by Terumo Co., Ltd.) attached with 2.5 cm, manufactured by Fuji Photo Film Co., Ltd., and removing coarse particles. An aqueous dispersion was obtained. The average particle diameter of the pigment-containing polymer particles was 80 nm.

  26.7 parts by weight of an aqueous dispersion of the pigment-containing polymer particles, 20 parts of an aqueous dispersion of the silica-containing polymer particles, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether, Surfynol 465 (Nisshin Chemical Industry Co., Ltd.) 1 part), 0.3 parts of Proxel XL2 (manufactured by Avicia Co., Ltd.) and 35 parts of ion-exchanged water were mixed, and the resulting mixture was filtered with a 1.2 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm). The aqueous ink 1 was obtained by filtering with a 25 mL needleless syringe equipped with Fuji Photo Film Co., Ltd.) and removing coarse particles.

Example 2
In Example 1, 26.7 parts by weight of an aqueous dispersion of pigment-containing polymer particles, 10 parts of an aqueous dispersion of the silica-containing polymer particles, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether, 1 part of Surfinol 465, Proxel Aqueous ink 2 was obtained in the same manner as in Example 1 except that 0.3 part of XL2 and 45 parts of ion-exchanged water were mixed.

Comparative Example 1
In Example 1, 26.7 parts by weight of an aqueous dispersion of pigment-containing polymer particles, 10 parts of glycerin, 7 parts of triethylene glycol monobutyl ether, 1 part of Surfinol 465, 0.3 part of Proxel XL2 and 55 parts of ion-exchanged water A water-based ink 3 was obtained in the same manner as in Example 1 except that was mixed.

Comparative Example 2
In Example 1, 5 parts of 40% hydrophilic colloidal silica (manufactured by Nissan Chemical Industries, Ltd .; trade name ST-40) was used in place of 20 parts of the aqueous dispersion of silica-containing polymer particles, and 50 parts of ion-exchanged water was used. A water-based ink 4 was obtained in the same manner as in Example 1 except that the above-mentioned parts were used.

Each of the water-based inks 1 to 4 obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was subjected to a bronze test, a gloss test, and a storage stability test as shown below. The results are shown in Table 1.
(1) Bronze test Using a commercially available inkjet printer [manufactured by Epson Corporation, model number: PX-A650], solid print on a commercially available special paper [photographic paper <gloss>, manufactured by Epson Corporation]] [Printing Condition = paper type: EPSON photographic paper, print quality: photo, color setting: no color correction], and left for 24 hours at 25 ° C., the resulting solid print was measured for bronzing by the following method.
The printed matter produced by the above method was mounted on a sample stage of a variable angle spectroscope GONIO-SPECTROMETER (manufactured by Murakami Color Material Research Laboratory, GSP-2), and a reflection spectrum at a wavelength of 390 nm to 720 nm was measured. The measurement conditions were as follows.
Incident angle 45 ° Receiving angle 45 ° Viewing angle 2 ° tilt angle 0 °
Light source: Halogen lamp C light From the spectrum thus obtained, the intensity at a wavelength of 550 nm and the intensity at 630 nm are examined, and the reflection intensity spectrum ratio (intensity at 630 nm / intensity at 550 nm) is calculated from the value. Evaluated.
(Evaluation)
Reflection intensity spectral ratio exceeds 4: Fluorescent lamps and sunlight reflected on the printed surface appear reddish.
The reflection intensity spectrum ratio is more than 3 and 4 or less: Redness is not easily recognized even when a photograph is printed.
Reflection intensity spectrum ratio of 3 or less: Red is hardly recognized even in solid printing, which is most preferable.

(2) Glossiness test The printed material obtained in (1) above was measured for gloss of 20 ° with a gloss meter (manufactured by Nippon Denshoku Co., Ltd., trade name: HANDY GLOSSMETER, product number: PG-1) (20 ° C. ). This value was evaluated as 50 or more, and 55 or more was more preferable.

(3) Storage stability A water-based ink is filled into a glass sealed container, and the average particle size after storage for 1 week at 70 ° C. is measured using a particle size measuring instrument (trade name: ELS-8000, manufactured by Otsuka Electronics Co., Ltd.). It measured by the following method and calculated | required the particle size increase rate from the following formula. When this numerical value is close to 100, the storage stability is good, and 90 to 110 is preferable.
(Average particle diameter after one month storage at 70 ° C./average particle diameter before storage) × 100

In addition, the measuring method of the average particle diameter of each water-insoluble polymer particle and silica particle is as follows.
Method for measuring average particle diameter of pigment-containing water-insoluble polymer particles and silica-containing water-insoluble polymer particles The average particle diameter was measured with a laser particle analysis system ELS-8000 (cumulant analysis) manufactured by Otsuka Electronics Co., Ltd. The measurement conditions are a temperature of 25 ° C., an angle between incident light and a detector of 90 °, and an integration count of 100. The refractive index of water (1.333) is input as the refractive index of the dispersion solvent. The measurement concentration was usually about 5 × 10 ⁻³ wt%.
The average particle diameter of the silica particles and the primary particle diameter of the pigment are 100 using a scanning electron microscope, and the number average particle diameter calculated from image analysis is used. In addition, when there exists a long diameter and a short diameter, it calculates using a long diameter.

    The aqueous inks of Examples 1 and 2 can efficiently suppress the bronze phenomenon as compared with the aqueous ink of Comparative Example 1, and can effectively suppress the bronze phenomenon as compared with the aqueous ink of Comparative Example 2. It was excellent in gloss and storage stability.

Claims (8)

A process for producing an aqueous dispersion comprising water-insoluble polymer particles (i) containing silica particles and a pigment excluding silica particles, comprising the following steps 1 to 3.
Step 1: Dispersing a mixture of silica particles, water-insoluble polymer (I ′), organic solvent and water
Step 2: A step of removing the organic solvent from the dispersion obtained in Step 1 to obtain an aqueous dispersion of water-insoluble polymer particles (i) containing silica particles.
Step 3: A step of mixing the water dispersion of the water-insoluble polymer particles (a) containing silica particles obtained in Step 2 and the pigment excluding the silica particles. The method for producing an aqueous dispersion for inkjet recording according to claim 1, wherein at least a part of the surface of the silica particles is hydrophobized. The method for producing an aqueous dispersion for inkjet recording according to claim 1 or 2, wherein the water-insoluble polymer particles (a) containing silica particles have an average particle size of 10 to 200 nm. The manufacturing method of the water dispersion for inkjet recording in any one of Claims 1-3 in which the pigment except a silica particle is contained as a water-insoluble polymer particle (b) containing the pigment except a silica particle. The water for inkjet recording according to any one of claims 1 to 4, wherein the content ratio of the silica particles and the pigment excluding the silica particles (silica particles / pigment excluding the silica particles) is 1/100 to 5/1 by weight ratio. A method for producing a dispersion. The method for producing an aqueous dispersion for inkjet recording according to any one of claims 1 to 5, wherein the pigment excluding the silica particles is a cyan pigment. The water-insoluble polymer (a ′) constituting the water-insoluble polymer particles (a) is copolymerized with a monomer mixture containing (a) a salt-forming group-containing monomer, (b) a hydrophobic monomer and / or (c) a macromer. The manufacturing method of the water dispersion for inkjet recording in any one of Claims 1-6 which is a water-insoluble polymer which becomes. A water-based ink for ink-jet recording, comprising the aqueous dispersion obtained by the production method according to claim 1.